jeudi 25 décembre 2008

Economics is the social science that studies the production, distribution, and consumption of goods and services.The term economics comes from the Ancient Greek ??????µ?a (oikonomia, "management of a household, administration") from ????? (oikos, "house") + ??µ?? (nomos, "custom" or "law"), hence "rules of the house(hold)".[1]Current economic models developed out of the broader field of political economy in the late 19th century, owing to a desire to use an empirical approach more akin to the physical sciences.[2] A definition that captures much of modern economics is that of Lionel Robbins in a 1932 essay: "the science which studies human behaviour as a relationship between ends and scarce means which have alternative uses."[3] Scarcity means that available resources are insufficient to satisfy all wants and needs. Absent scarcity and alternative uses of available resources, there is no economic problem. The subject thus defined involves the study of choices as they are affected by incentives and resources.Economics aims to explain how economies work and how economic agents interact. Economic analysis is applied throughout society, in business and finance but also in crime,[4] education,[5] the family, health, law, politics, religion,[6] social institutions, war,[7] science and research.[8] The expanding domain of economics in the social sciences has been described as economic imperialism.[9][10]Microeconomics==============A common distinction is between positive economics (describing "what is") and normative economics (advocating "what ought to be") or mainstream economics (more "orthodox") and heterodox economics (more "radical"). The primary textbook distinction is between microeconomics ("small" economics), which examines the economic behavior of agents (including individuals and firms) and "macroeconomics" ("big" economics), addressing issues of unemployment, inflation, monetary and fiscal policy for an entire economy. Microeconomics looks at interactions through individual markets, given scarcity and government regulation. A given market might be for a product, say fresh corn, or the services of a factor of production, say bricklaying. The theory considers aggregates of quantity demanded by buyers and quantity supplied by sellers at each possible price per unit. It weaves these together to describe how the market may reach equilibrium as to price and quantity or respond to market changes over time. This is broadly termed demand-and-supply analysis. Market structures, such as perfect competition and monopoly, are examined as to implications for behavior and economic efficiency. Analysis of change in a single market often proceeds from the simplifying assumption that behavioral relations in other markets remain unchanged, that is, partial-equilibrium analysis. General-equilibrium theory allows for changes in different markets and aggregates across all markets, including their movements and interactions toward equilibrium.[11][12]Another distinction is between mainstream economics and heterodox economics. One broad characterization describes mainstream economics as dealing with the "rationality-individualism-equilibrium nexus" and heterodox economics as defined by a "institutions-history-social structure nexus".Markets=======Production possibilities, opportunity costMain articles: Production-possibility frontier, Opportunity cost, and Production theory basicsIn microeconomics, production is the conversion of inputs into outputs. It is an economic process that uses resources to create a commodity that is suitable for exchange. This can include manufacturing, warehousing, shipping, and packaging. Some economists define production broadly as all economic activity other than consumption. They see every commercial activity other than the final purchase as some form of production.Production is a process, and as such it occurs through time and space. Because it is a flow concept, production is measured as a "rate of output per period of time". There are three aspects to production processes, including the quantity of the commodity produced, the form of the good created and the temporal and spatial distribution of the commodity produced.Opportunity cost expresses the idea that for every choice, the true economic cost is the next best opportunity. Choices must be made between desirable yet mutually exclusive actions. It has been described as expressing "the basic relationship between scarcity and choice."[14]. The notion of opportunity cost plays a crucial part in ensuring that scarce resources are used efficiently.[15] Thus, opportunity costs are not restricted to monetary or financial costs: the real cost of output forgone, lost time, pleasure or any other benefit that provides utility should also be considered.from Wikipedia.